Generally, an LED is eco-friendly and a response speed of the LED is a nanosecond. The LED is able to respond rapidly and it is effective in a video signal stream. The driving of the LED can be impulsive and color reproduction of the LED is 100% or more. Brightness, a color and the temperature thereof may be freely changed by adjusting the radiation intensity of red, green and blue LEDs. Such the LED has advantages that are proper to make a liquid crystal display (LCD) panel light, thin, short and small. Accordingly, the LED has been utilized as a light source for a backlight of such a LCD panel in recent.
In addition, a plurality of LEDs are connected with each other to enlarge the output from a lighting apparatus using a LED. In this instance, voltages more than the total voltages gained by adding up forward driving voltages of LEDs connected in serial have to be supplied, to drive the plurality of the connected LEDs.
In the lighting apparatus using the plurality of the LEDS, an electric voltage using switching mode power supply (SMPS) is used to drive the lighting apparatus at a broad range of voltages.
However, a conventional LED driving apparatus using the SMPS uses high speed switching and much noise might be generated. Accordingly, the conventional LED driving apparatus requires a noise filter and is uses many parts for circuit formation. It is difficult to form a circuit with a low production cost.
In addition, the conventional LED driving apparatus uses an electrolytic condenser and it is inappropriate for a long life space of usage. Most of LED lighting apparatuses include a LED for emit a light and a circuit. The heat generated by the luminosity of the LEDs might shorten the life span of the electrolytic condenser disadvantageously.
Voltages more than the voltages or more gained by adding forward operating voltages of the LEDs have to be supplied to drive the lighting apparatus having the plurality of the LEDs connected with each other. Accordingly, it is difficult in environments having large variation of the input voltages to provide a high power factor LED lighting apparatus.